As shown in FIG. 7, the existing spiral conveying mesh chain is driven by a rotary drum. The rotary drum cooperates with the spiral conveying mesh chain through square passive tooth and driving tooth in transmission manner. When the passive tooth of the spiral conveying chain mesh rotates, the force direction k between the passive tooth and the driving tooth is outwardly deviated relative to the driving direction j of the spiral conveying mesh chain. When the spiral conveying mesh chain has relatively small tightening force on the rotary drum, the passive tooth of the spiral conveying mesh chain tends to separate and detach from the square driving tooth on the rotary drum, as a result, the spiral conveying mesh chain cannot rotate with the rotary drum accordingly.